Method for the removal of suspended material from gases



Jan. 1 7 1924 E. R. WOLCOTT METHOD FOR THE REMOVAL OF SUSPENDED MATERIAL FROM GASES Filed March 14, 1919 M o r w d 8 a 5 E L w 5 9%; w 7 W 4 j Patented Jan. 1, 1924.

EDSON R. WOLCOTT, LOS ANGELES, CALIFORNIA, ASSIG NOR 'IO INTERR'ATIONAL PRECIPITATION COMPANY, 015 LOS ANGELES; CALIFORNIA, A CORPORATION OF CALIFORNIA.

METHOD FOR THE REMOVAL OF SUSPENDED MATERIAL FROM GASES. A

Application niedimarn 14, 1919. Serial no. 282,700.

To all whom it may concern:

Be it known that LEnsoN R. WOLCOTT, a citizen of the-United States, residing at Los Angeles, in the county of'Los Angeles and State of California, have invented a new and useful Method for the Removal of Suspended Material .from Gases, of which the following is a specification.

This invention relates to the art of re moving dust and fume from hot furnace gases and is particularly applicable in connection with the separation and removal of suspended material from gases passing from Portland cement kilns. It has been attempted to remove and recover such suspended material by the actionof water sprays, and similar means, but while such sprays are effective to a certain extent they do not remove more than a certain proportion of the suspended material.

of a wet collecting system'has, however, the advantage in connection with the removal that it recovers in the form of solution certain soluble constituents of such dust and fume, particularly potassium salts, constituting a valuable by-product of the cement industry.

Electrical precipitation has also been used successfully in collecting suspended material from cement kiln gases and it has been found of advantage in certain cases to carry out the electrical precipitating operation in such manner that the suspended material is collected in the presence of sufficient water or solution to form a fluid in which the soluble constituents of the dust and fume eventually becomerdissolved. In such an operation the difiiculty has arisen that scales or incrustations are liable to be formed on the collecting surfaces requiring frequent cleaning and interfering with the continuous operation of the process-and the main objects of the present invention are to ef feet a higher concentration of potash in the precipitator, eliminate the incrustations formed therein, and in general increase; the efliciency of operation.

Another object of the invention is to provide for securing effective operation of an electrical precipitator in collecting dust and fume in a liquid film while at the same time preventing the formation of scales or in- The use orustationson or in the electrical precipitator.

In the accompan ing drawin Fi 1 is a longitudinal section of a'du; and fume collecting apparatus for carrying out my invention. v Fig. 2 is a transverse section on line 22 an Fig. 1 showing merely the body of the Referring to the drawings, theflue indicated at 1 is connected to receive the efiluent gases from a cement kiln, being, for 6 example, connected to the stack base 2 of a cement kiln 3, the stack base being provided with means for normally directing the entire or any desired proportion of the kiln gases into the flue 1, said flue is provided at 7 I various points along its length with water distributing means 4, which may be spray nozzles, or atomizers, operating either by pressure, or by rotary or other, mechanical means, in wellknown manner to spray and "I5 of dust and fume from cement kllIl gases distribute water in finely divided condition throughoutrthe body of gas passing through the flue, preferably in such manner as to saturate, or approximately saturate, the gases with water. At a part of the flue beyond the several water sprays 4 is provided a screen or filter 5 extending transversely in the flue so as .to intercept the gases passing therethrough. This filter may be made of metallic screen in, layers withifstaggered mesh, or of coke, or of asbestos, excelsior,

or other suitable material. The bottom of the flue 1 is preferably inclined so as to drain the liquid to outlets 6. A water supply pipe 7 leads to the respective nozzles 4 and is preferably provided with a branch 8 having a valve 9 and discharging into or onto the filter or screen 5.

' An electrical precipitator, indicated at 10,

is connected to receive the gases from the flue 1 and is provided with suitable means,

such as collecting electrodes 11, formed as vertical pipes and discharge electrodes 12, mounted on insulated frame 13 and extend-' v ing within said pipes for maintaining an I00 electrical field through which the gases are passed. The casing of the electrlcal precipitator is provided at its lower portion with suitable means, such as funnel 15, for drawing oflz' collected material and at its upper portion with a header 16, communi.

the flow of liquid collected eating with an outlet stack 17 If necescause more or less condensation of water sary, suitable means, such as a fan or blower upon the walls or flues of the precipitator, 18, may be provided for maintainingdraft either directly or by precipitation of conthrough the apparatus. The discharge elecdensed .fo'g produced by such cooling of the trodes 12 are connected to any suitable saturated gases. By this means sufiicient means, for example, as disclosed in patent liquid may be caused to collect on the walls to F. G. Cottrell No. 895,7 29-August 11th, of the precipitator to form with the precipi- 1908, and the casing 14 is preferably tated suspended material (dust or fume) a grounded. A damper or gas flow restrictfluid deposit or film which runs down on the ing means 19 may be provided between walls or collecting electrodes of the precipifilter means 5 and the electrical precipitator tator, whereby the precipitate is continually to cause expansion of the gas with resultant recovered from the electrodes and no especial cooling and condensation of moisture in the cleaning means is required. form of fog-or lb'iid, such condensation The liquid or sludge drawn oil from the taking place largely on the solid suspended delivery means 15 may be suitably treated to particles and on ions produced in the elecremove the liquid from the solid portions trical precipitator, acting as nuclei. The thereof and part or all of the liquid so obprecipitator 1O may be cooled by circulatained may be returned to the spray devices tion of atmospheric air, or other cooling through pipe 7 in any suitable manner so as medium, around the electrodes 11. etc provide for accumulation or progressive It is to be understood that any other suitconcentration of the resulting solution; the able form of electrical precipitator may be same is true of the liquid or sludge drawn used instead of the form herein shown but off at the outlets '6, which represents the exit is preferred to use a form with vertically cess of liquid supplied to the gases beyond extending collecting electrodes to facilitate that which is required for humidification or material downsaturation, together with any solid material washed out of the gases by the spray means 4, or in the filter 5. The liquid obtained in wardly on same.

- The process is carried out in the above described apparatus as follows:

The hot gases coming from the kiln pass solids separating therefrom may be treated through the flue 1 and are therein humidified in any suitable manner for recovery of soluration (preferably to approximate saturaafter asuitable state of concentration has tion) and the gases then pass through thebeen reachedand, in that case, a portion of filter or screen 5, wherein the heavier solid such liquid may from time to time, or conparticles carried in suspension by the gases tinually be Withdrawn from the apparatus are filtered out thereby eliminating most for such treatment, the remainder being of the solid particles of the raw mix carried turned to the spray. devices, together With out of the kiln by the hot gases and thus more or less fresh water. If desired, howse arating these heavy particles from the ever, fresh water only may be introduced b al ali garticles which are vactually volatithe spray devices'and the solution obtaine lized. n this way most of the lime islsepfrom the outlet means 6 and 15-may be evaparated from the potash, thereby increasing orated to dryness, or otherwise treated for the potashconcentration and eliminatingthe recovery of solubles without returning any difiiculties of incrustation, which are due part of the liquid to the spray devices. largel to the resence of calcium salts in What I claim is: the so ution. T e filter or screen 5 is washed 1. The method of removin suspended maor flushed intermittently or continually terial from gases, which consists in distribut- With water or solution sup lied by means ing water into such gases to humidify the 8 and thereby kept clean.

herent deposit is formed on the filter and is w dfil ri g medium to fi e out part-of not removable by washing, the filter may be the suspended matter and to further hution' to precipitate suspended material thereremoved. The gases pass from the filter or midify' the gases, and then subjecting the screen 5 to the electrical precipitator 10, gases to the action of an electrical field to wherein they are subjected to electrical acprecipitate suspended material therefrom,

the gases and the precipitated material befrom. ing subjected to cooling action in such man- 'An important effect of the water sprays ner as to cause condensation of water from and the subsequent passage of the gas the water vapor present in the gases, and colthrough the filter is that the gases are thorlection of such/condensed water with the oughly or substantially saturated with water precipitated material. vapor and in passing to and through the 2. A method, according to 01am 1, whereelectrical precipitator are cooled (by con-- in the gases are caused to expand after passduction through the walls andjby expansion ing through the filtering medium to cause at the damper 19, if desired) sufliciently to Cooling and condensation of moisture in the the manner above described and also the n, case an adsame, then passing the gases through a to a condition of more or less complete satubles, or other valuable constituents thereof,

form of fog, such f0 precipitated along wi terial by the action 0 3. The method of r 5 nace gases suspended material, inc

lime and soluble salts, Which spraying water into the gases to s same, then passing the gases thro g bein subse uently th the uspend%d maf the electrical field.

emoving from hot furluding' consists in aturate the ugh a filtering medium to remove suspended material, 10 including some of the lime, from the the abo ve operations being carried gases, out in such manner as to substantially saturate the gases with moisture, and then passing the gases through anelectrical field to precipitate suspended material and reducing the 1 In testimony whereof I have hereunto sub- 20 scribed my name this 5th day of March, '1919.

' E-DSON R. WOLGOTT. 

